Thanks for the kind words folks.
Man I've really been spending a lot of time working on this plane - it's coz I'm flying it in the Convoy Trucking server to get my 500 flights achievement - as a result any errors quickly become annoying.
Thanks to the good help and references by [DRuG]Dingleman, I have been able to remove the seam/line that ran down the centre of the model, then add flashing lights using rwanalyse. Following this, there was little left to annoy me - using a tip from Dingleman on gtaforums, I have welded vertices in a number of areas which has left the model behaving beautifully when the light falls off it. After this I tweaked the ailerons a bit more & I gotta say, I reckon the model is looking pretty good.
Enjoy the update - link updated in first post and an gtagarage.